You need to let them out several times a day. When you let them out keep repeating to them, “go potty”. If they dont go walk them around a little. If they go praise them alot and maybe even give them a treat. You have to do this every time you let them out. If you think they need to go then ask them if they need to go outside and take them out.

Get two small crates and crate train them. You should crate them when they cannot be watched and taken out 15 minutes after eating, right after drinking, playing, sleeping, and being taken out of the crate, once every 1-2 hours, and right before you put them in the crate.

The crate should only be big enough that they can stand up, turn around, and lay down in.

Okay, im just a kid but i really wanted a dog once so i read heaps up about it. You will need quite a bit of time for this. What you need to do, about 1 hour after they have eaten take them out side and tell them the command that you want to use. Put them where you want them to go. Once they have gone give HEAPS of praise. Repeat this, eventually they will know that a while after they eat they will have to go out side (if you have constantly done the procedure) and do their business. They will also reliese that they will be praised for doing it. Eventually it becomes second nature. If they ever do it inside make sure you let them know its naughty.
Hope I helped
Cuzza4321